Heat and Physical Activity

This indicator incorporates temperature, humidity, and solar radiation restricting analysis to local sunlight hours only to estimate and track the daily hours per person during which undertaking outdoor physcial activity would pose a heightened heat stress risk. The indicator uses the updated 2024 Sports Medicine Australia Extreme Heat Policy, which applies the Predicted Heat Strain model (ISO 7933:2023) to estimate heat stress risk during brisk outdoor walking. Exposure is tracked at two levels: "any" risk (at least moderate), requiring additional rest breaks and active cooling, and "extreme" risk, at which physical activity should be avoided entirely.

This indicator estimates heat stress risk by exercise category but does not account for differences across population groups. Risk may vary for older adults, young children, pregnant women, and people with disabilities or chronic diseases. A more comprehensive model would incorporate individual characteristics such as age, health status, physiology, and clothing. Population estimates assume annual counts apply uniformly to every hourly grid cell, despite likely variations in population movement. Although this simplification may reduce accuracy at finer scales, it provides a reasonable country-level approximation of population exposure.